Tests for ProxyGenerator.CreateProxy throwing Null Reference Exception

Here are two tests I put together around issue #174 that ProxyGenerator throws a null reference exception if a property on the likeness source is null.  The first test correctly passes when the source properties are non-null (in these tests, a single string property), but the second with a null source property fails.  The exception being generated is a NullReferenceException within the AreOrderedBy method of ProxyGenerator.  Do these tests properly demonstrate this issue?